1. Field of the Invention
This invention pertains to dynamically adjusting the accept/reject level of an electronically controlled sorting machine in accordance with the actual objects being sorted.
2. Description of the Prior Art
This invention may be used with many types of sorting machines used for sorting different kinds of objects or products. A typical sorting machine of the type envisioned for this invention is a color food sorting machine comprising many different components in order to electronically discriminate unacceptable from acceptable food products and mechanically separate (i.e. sort) the bad from the good. These components are generally comprised of one or more lighting illumination sources; optical assemblies for viewing, focusing, and light wavelength filtering; photocell detectors for converting light energy into electricity; and various electronic circuits for amplifying, conditioning and classifying resultant signals into acceptable and unacceptable occurrences. For multiple channel sorting machines, multiple sets of these various components are packaged into one machine. An example of a typical system is the COLORWATCH System No. 490033 of ESM International, Inc.
In most instances, a sorting machine electrically discriminates unacceptable from acceptable products by optically detecting the color of the product and comparing it to a minimum acceptable color. If the product's color does not meet the minimum requirement, the product is rejected.
In order to remove the rejected product, such machines include an ejector mechanism located downstream from the sensor or sensors and actuated by an electrical signal originating from sensor detection. When a substandard product is detected, an electrical actuating signal is produced and the ejector is actuated just as the substandard product and the mechanism are in alignment. Therefore, there is a slight delay between detection and ejection.
Even though some sorting machines are more efficient than others, none are mechanically perfect. All machines presently in the market capture at least some objects that should have been rejected. The percentage of error due to the mechanical deficiency is consistent for a given machine. However, these mechanical limitations are amplified when there are significant variations in the products over the area of interest. For example, a growth rate of a product such as a tomato may be inconsistent throughout a field. The sorter may pass over an area where most of the tomatoes should be rejected because of the unacceptable color. Inevitably in such a situation, more unacceptable products will be classified as acceptable than should be because there are more unacceptable products present.
These limitations can have a profound impact on any given industry, and in particular the farming industry. For example, when a farmer harvests a field of tomatoes and sells them to a cannery, his paid tonnage for tomatoes is subject to dockage in relation to the quality of his fruit. One of the measures of quality is the degree of "color quality" (ripeness) of the tomatoes. A farmer can be penalized to the point of complete rejection of a load of fruit if during the sampling process it exceeds the state tolerance of green tomato content.
Tomato fields may have areas that contain a preponderance of "green" or "breaker" (immature) tomatoes. Traditionally a farmer is forced to sacrifice a portion of his deliverable fruit by setting his equipment to accept only tomatoes that are red ripe in order to insure that his overall color quality requirements are met.
Therefore, it is a feature of the present invention to provide an improved method of dynamically adjusting the accept/reject level of an electronically controlled sorter to obtain true color average in a load of sorted objects thus minimizing the amount of products rejected.
It is another feature of this invention to provide an improved method of automatically making a sorting machine more sensitive in areas that contain a high percentage of unacceptable product.
It is yet another feature of this invention to provide an improved method of optimizing the sensitivity of the sorter particularly in areas where the effects of mechanical limitations of the sorter become more prevalent.